This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Utility Model Application 201 07 885, filed on May 10, 2001, the entire disclosure of which is incorporated herein by reference.
The invention relates to a device using a flow of air for holding the leading ends of weft threads that have been pneumatically inserted into an open loom shed of an air jet loom.
In air jet looms it is generally known to arrange a weft thread holding device in the form of a suction device in the area of or adjacent to a weft tensioning or stretching device at the weft exit side of the loom shed. After a respective weft thread is pneumatically inserted and beat up against the beat-up edge of the woven cloth, the free leading end of this weft thread is pneumatically engaged by the suction of the suction device and then suction-held until the respective weft thread is tightly bound in to the woven web and into at least one catch selvage that is formed along the edge of the woven cloth.
A disadvantage of the known weft holder device embodied as a suction device is that it requires a source of vacuum or suction for developing the required suction for pulling and holding the weft thread end in the holder device. This suction is typically provided by a vacuum unit, or particularly a so-called ring compressor, which provides the required vacuum suction to the suction nozzle of the weft holder device. Such a conventional ring compressor is relatively large and therefore requires a rather large installation space at the side of the weaving loom. Moreover, such a ring compressor adds a considerable additional cost.
In view of the above, it is an object of the invention to provide a weft holder device for holding the leading ends of weft threads at the downstream or weft exit side of a loom shed, whereby this weft holder device does not require a suction device for its operation. More particularly, it is an object of the invention to provide a weft holder device that can operate with readily available pressurized air rather than requiring a vacuum suction supply. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a weft holder device for holding the leading ends of weft threads at a side of an air jet loom, wherein the weft holder device comprises a device body having a pressurized air flow channel therein, and a pressurized air outlet arrangement adapted to introduce pressurized air into the flow channel, so that the leading ends of weft threads inserted into the loom shed and protruding from the exit side thereof are brought into and temporarily held in this flow channel by a flow of pressurized air.
In a particularly preferred arrangement, the device body includes an opening extending through the device body in a direction parallel to the weft insertion direction, whereby the weft thread ends are inserted into this opening as they exit from the side of the loom shed during the weft insertion. The opening has a tapering funnel shape as seen from the loom side or on a vertical section plane extending parallel to the warp threads, whereby the opening tapers into a narrower slot in the beat-up and cloth drawing-off direction. The pressurized air flow channel preferably communicates and extends downwardly from the slot. Thereby, the weft thread ends are first inserted into the opening, then move into the slot as the weft threads are beat-up against the beat-up edge of the woven cloth, and then are pushed down into and held in the pressurized air flow channel by a flow of pressurized air applied by the pressurized air outlet arrangement.
The device body of the weft holder device is preferably arranged stationarily and fixedly relative to the loom machine frame, for example on a cloth spreader or temple. More particularly, the weft holder device may be arranged stationarily at a location between a weft thread detector or stop motion and a weft thread stretching or tensioning device that are each mounted on or connected to the weaving reed, so as to be movable therewith. The funnel shaped, elongated tapering configuration of the opening of the weft holder device, leading and tapering into the narrower slot, allows for the beat-up motion of the weft threads and the drawing-off of the woven cloth, together with the beat-up motion of the weft stop motion and the weft tensioning device. The device body of the weft holder device is arranged in such a manner at the weft exit side of the loom shed so that the pressurized air flow channel extends perpendicularly to the beat-up edge of the woven cloth, and particularly on a plane that is perpendicular to the beat-up edge of the woven cloth.
The weft holder device according to the invention achieves the advantage, that its operation requires only the supply of pressurized air, which is typically already available in an air jet loom. The inventive arrangement completely avoids the need for a ring compressor as well as a suction nozzle in the area of the weft thread stretching or tensioning device, and thus also omits various hoses and the like, which leads to a considerable savings or reduction of cost, space, and complexity.
Additionally, the inventive weft holder device improves the operating characteristics and performance of the loom, because the weft holder device securely holds the loose weft thread ends, and thereby prevents the formation of undesirable loops in the weft thread ends, and the undesirable tucking-in of the weft thread ends back into the cloth selvage.